1. Field of the Invention
The present disclosure relates generally to fermentation devices and methods for the making of wine, and more particularly to a disposable wine fermentation vessel with cap management and integral press.
2. Statement of the Prior Art
Modern winemaking typically comprises combining winemaking ingredients in a clean, essentially sterile fermentation vessel with minimal introduction of air. For the production of red wine, these ingredients include grape skins which must be separated after fermentation. This separation operation is traditionally performed in a press.
In the fermentation of red wine, the grape skins present in the fermentation tend to float up to the top of the liquid in the fermentation vessel and form what is termed a “cap.” This cap needs to be periodically broken up so that the skins may be mixed into the liquid in order to extract color and flavor compounds from the skins and seeds. The cap must also be kept moistened to prevent the growth of deleterious aerobic bacteria. Traditionally, the agitation of the cap has been done by poking the cap with a pole to break it up. This is termed “punch down” and even automated punch down devices are available. These are usually mechanically complex and require a moving seal to prevent contamination of the fermenting wine. More modern methods include pumping the liquid in the fermenter over the cap to break it up.
Other techniques include using horizontally rotating fermentation vessels such as those described in U.S. Pat. No. 4,474,890 (Rieger) and published European patent application EP0337060 (Speidel) that force the cap into the liquid. These are expensive and complex machines with large rotating assemblies, making them impractical for most wineries. U.S. Pat. No. 6,703,055 (Klein et al.) also describe a fermentation vessel with rotating mechanical agitators to flood the cap when needed. Cap management is a major factor in red wine production, since it has a tremendous impact on the wine's color and flavor, and thereby determines the value of the resulting red wine.
At the conclusion of the fermentation, the contents (i.e., fermented juice, spent skins, and yeast) are typically pumped to a press where the fermented juice is separated from the skins, seeds, and dead yeast. This is a complex and labor-intensive operation, and requires the press to by emptied and cleaned multiple times. Presses are very prone to clogging and must be emptied and cleaned manually to continue the pressing operation. Multiple transfers between the equipment also increases the risk of contamination. This problem is well recognized and there have been some attempts in the prior art (e.g., U.S. Pat. No. 7,552,675 (Lorincz) and U.S. Pat. No. 7,891,291 (Lorincz)) to develop fermentation vessels that have integral pressing capabilities. These attempts too are very complex and expensive machines with hydraulic rams under computer control. Solids, which are called “pomace” and consist of skins, stems, seeds and dead yeast, are left behind in the fermentation vessel and requires personnel to enter the vessel and shovel it out.
In certain winemaking operations, the contents of the fermentation vessel are allowed to settle and then the clarified fermented juice is removed, leaving the spent “lees” (i.e., the deposits of dead yeast or residual yeast and other particles that precipitate, or are carried by the action of “fining,” to the bottom of a vat of wine after fermentation and aging) behind. This is traditionally done by siphon which takes considerable time. Transfer can be speeded up by pressurizing the fermentation vessel, but this requires the fermentation vessel to be pressure rated—considerably increasing the cost. U.S. Pat. No. 8,015,915 (Puissant) describes a fermentation vessel with internal lees containment, but this comprises a very complex conical vessel and expensive mechanical apparatus. It can be seen, therefore, that a need exists in the winemaking process to rapidly transfer liquids from one container to another without contamination.
Another major issue, especially for smaller wineries, is the disposal of waste wash water. Traditionally, winemaking equipment is made of stainless steel and this equipment must be cleaned before and after each use. The wash water contains a high biological load due to the spent grape skins and yeast. The water may also contain large amounts of harsh detergents and disinfecting chemicals. This waste water can amount to as much as 10 times the fermentation vessel volume and must be treated before discharge to streams or municipal treatment facilities. The capital and operating cost of this waste treatment can be prohibitive to a small winery. Furthermore, many communities restrict the water usage and also the discharge of waste water in order to protect the environment. Embodiments of the present invention overcome this problem by providing a pre-cleaned fermentation vessel comprising a single-use plastic bag. At the end of the fermentation, the fermented juice is pressed and most of the solids (i.e., pomace) are retained in the plastic bag which can then be disposed of as solid municipal waste or landfill. This eliminates almost all the washing requirements and manual cleaning operations.
Thus, there are four important problems to be solved in the wine fermentation process, particularly with red wines: i) a means to provide a clean, preferably sterile, anaerobic environment for the fermentation to prevent contamination; ii) a means to agitate the cap to extract flavor and color from the skins; iii) a means to press out the fermented juice without the need to transfer to another vessel; and finally iv) a means to perform all these functions with a pre-cleaned single-use disposable fermentation vessel that generates minimal waste wash water and eliminates labor-intensive cleaning. As will be evident from the description, embodiments of the present invention overcome all these problems.